Driving mechanisms of this type can be used, in particular, for lifting head and leg pieces of arm-chairs and beds, for orienting dish aerials, as well as for remote controlling any kind of inaccessible levers.
The purpose of the invention is to provide a driving device for the above-mentioned uses, in such a way that, with very reduced room requirements, the driving device can feature a very wide displacement range and the various elements constituting the device can be of a very simple arrangement and assembly and can be manufactured at very low cost price.
To these ends, a driving device of the aforesaid type is essentially characterized in that, being arranged according to the invention, it comprises a motor driving, around its shaft, a winding element pulling a mobile lifting element attached to a fixed point used as anchoring point for the flexible and sliding element, perpendicularly to the axis of the thus constituted pulling block mechanism, in a tube-shaped guide inside which it is housed and compressing a return spring ensuring the return in extension of the mobile element, in such a way that this device works in traction and without any buckling stresses. Preferably, demultiplying means are provided in order to increase the performances of the device; advantageously said demultiplying means include at least a roller arranged as a pulley block, and practically several rollers arranged as a stepped or multistage pulley block around which the winding element winds up and which, preferably, may be selected from a metal strip, a chain, a flexible sling rope, such as a steel string or music wire.
It is therefore possible to constitute the device with very low room requirements, especially as to height, making it possible for example to incorporate same without any difficulty in a bed framework, thereby avoiding that the pieces or parts of pieces be in projection and may injure the user.
To stabilize the mobile element moved by the device and in order to ensure that it remains parallel to a reference direction (particularly in the case of a raisable end of a bed), it is of interest that the mobile element be connected to a coaxial tube supporting pairs of opposite arms mutually in engagement with their adjacent ends respectively and in hinged connection by their other end to the two mutually displaceable parts under the action of the driving device, whereby said arms forming at least a deformable rhombus ensure a mutually parallel displacement of both parts.